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Abstract
This thesis comprises spectroscopic studies of two series of glasses, namely calcium borate and calcium phosphate doped with definite additives 0.05 mole% chromium oxide, vanadium oxide and iron oxide. The work includes UV-visible and infrared spectroscopic measurements of the prepared glasses before and after successive gamma irradiation. The glasses were prepared from chemically pure raw materials. The calcium borate glasses were melted in platinum crucibles at 1100 – 1150 °C for two hours while the calcium phosphate glasses were melted in alumina crucibles at 950 – 1000 °C. After complet melting and homogenizing, the melts were cast and annealed at the appropriate temperature. The glass samples for UV-visible spectrophotometric are the dimensions (20 x 10 x 2) (mm)3 and were perfectly grounded and polished and the measurements were carried out by a recording spectrophotometer in the range 200 – 1000 nm. Infrared spectra of the glasses were investigated for fine powder by the KBr technique using a recording FT/IR spectrometer in the range 350 – 2000 cm-1. Experimental infrared spectra of the different glasses reveal the following data: 1- The base calcium borate glass reveals infrared absorption bands which are characteristic of bond vibration of different boron-oxygen network of triangular and tetrahedral boron oxygen groups including pentaborate, triborate, diborate, metaborate, orthoborate and pyroborate. 2- The infrared spectra of all the Ca-borate glasses are quite similar but the intensity of the bands changes with composition of the glass. 3- The infrared absorption spectrum of calcium phosphate glass reveals absorption bands which are characteristic to several P-O linkages such as symmetric and antisymmetric O-P-O and P-O-P vibrations and that due to P=O end group beside the hydroxyl groups in the form of either free OH-, H2O or P-O-H. 4- The change in the composition of the glass causes obvious variation in the intensity of the absorption bands. UV-visible absorption spectra Optical absorption spectra of the undoped unirradiated calcium borate glasses reveal a cut-off band which shifts to longer wavelength by increasing the CaO content in the calcium borate glass. On subjecting this glass to successive gamma irradiation induced UV and visible band are resolved. The calculated induced spectrum reveals five induced-bands extending in the ultraviolet and visible regions. Spectral measurement of Cr-doped calcium borate glass reveals a cut-off in the UV and two visible bands and this spectrum indicates the presence of chromium in two valence states, namely Cr6+ and Cr3+. On subjecting the Cr-doped Ca-borate glasses to successive gamma irradiation, the color changes from green to deep brown and the absorption bands are shifted to lower wavelengths. The induced spectra reveal 7 induced bands in the UV-VIS regions. Spectral measurement of V-doped calcium borate glass indicates the observation of a UV cut-off at 380 nm and a visible band at about 590 – 610 nm. On subjecting this glass to gamma irradiation, the UV cut-off shifts to longer wavelength and the visible band reveals higher intensity. The induced spectrum reveals seven induced bands in all the UV-VIS regions. Spectral measurment of Fe-doped calcium borate glass reveals a cut-off in the range 350 – 400 nm. On subjecting the glass to gamma irradiation, a visible band is observed beside the UV cut-off. The induced spectrum reveals 6 induced bands extended in the UV-visible regions. Optical absorption spectra of the undoped calcium phosphate glasses reveal no visible bands but shows an UV cut-off at 328 nm. On subjecting the glasses to gamma irradiation a visible band is resolved. The induced spectrum for the calcium phosphate glass reveals 6 bands extending in the UV-visible region. The Cr-doped calcium phosphate glass spectrum reveals an UV-cut-off and two visible bands at 430 nm and a triply splitted band with peaks at 630, 650, 680 nm. On subjecting this glass to gamma irradiation, aslight change is observed. The induced spectrum of Cr-doped glass reveals six bands. The V-doped calcium phosphate glass spectrum reveals an UV cut-off and two visible bands. On subjecting this glass to gamma irradiation, a shift of the UV cut-off and is overlapped by the first visible band. The induced spectrum reveals 8 induced bands. The Fe-doped calcium phosphate glass spectrum reveals an UV cut-off and a broad near-infrared band at about 965 nm. On gamma irradiation, a new visible band is observed at 547 nm. The induced spectra reveals eight induced bands. The experimental results are interpreted on the following basis 1) For the infrared absorption spectra, it must be recalled that: a) The midinfrared region 2000 – 400 cm-1 is characterized by the appearance of the characteristic bands due to the vibrations of borate network in different arrangements. b) The near-infrared region is characterized by the absorption due to water, hydroxyl or BOH groups. c) The borate groups consist of tetrahedral BO4 groups which are generally showing their vibrational modes in the 800 –1200 cm-1 region while the borate groups consisting of triangular BO3 groups reveal their vibrational modes in the 1200 – 1600 cm-1 region. d) The infrared absorption spectra of the phosphate glasses are spread over the whole measured regions (400 – 1400 cm-1). e) The IR absorption spectra in the region 850 – 1200 cm-1 in the phosphate glasses are found to be sensitive for the different metaphosphate groups in different forms. f) The P=O double bond is found to be more strongly localized in the central position of the phosphate groups. 2) For the UV-visible optical absorption spectra, the following criteria are introduced: a) The shift of the absorption band in Ca borate glass to longer wavelength is attributed to the conversion of BO3 to BO4 without the creation of nonbridging oxygen ion. b) The intrinsic induced bands upon irradiation of the base undoped borate glass are analyzed and some of them lie in the vicinity of the alkaline earth cations and the others are not. c) The Cr-doped calcium borate glass reveals an UV band which is related to Cr6+ ions and two visible bands which are associated whith Cr3+ ions. Irradiation of Cr-doped calcium borate glass produce induced defects due to combined effects of intrinsic base borate glass and a possible photochemical reaction of Cr6+ electron capturing Cr3+ d) The V-doped calcium borate glass reveals an ultraviolet band and a visible band and they are correlated with V3+ ions. Irradiation of this glass increases the intensity of the bands which are related to progressive growth of the induced defects. e) The Fe-doped calcium borate glass reveals the same characteristic ultraviolet bands which are related mostly to Fe3+ ions and usually observed in most commerical glass due to iron impurities. Irradiation of this glass increases the intensity of the UV bands which are related to the possible photochemical conversion of some Fe2+ to Fe3+. 3) In the base undoped calcium phosphate glass, the introduction of divalent oxides (M-O bonds) are assumed to shift the UV cut-off to longer wavelengths similar to the silicate glasses. On irradiation, numerous induced defects are generated which can be attributed to electron or hole traps. a) Cr-doped calcium phosphate glass reveals an ultraviolet band which is related to Cr6+ions and two visible bands originating from Cr3+ ions. Gamma irradiation of this glass produces an ultravaiolet and another visible band with two-split peaks and the changes are related to both the intrinsic induced defects of the host glass and the possible photochemical reaction of chromium ions. b) The V-doped calcium phosphate glass seems to contain the three possible valencies of vanadium (V3+, V4+, and V5+) with ratios depending on the nature and composition the glass and condition of melting but the color of the glass indicates the presence of high ratio of V3+ ions. Gamma irradiation of this glass is observed to reveal spectral variations which are attributed to the comined effect of induced defects from the host glass and some possible photochemical process of the three valence states of vanadium ions. c) The Fe-doped calcium phosphate glass reveals charge transfer UV bands which are mostly related to trivalent Fe3+ ions. Gamma irradiation causes the increase of the intensity of absorption bands and the induced bands are correlated with both the sharing of the induced bands from the host phosphate glass and photochemical conversion of some of the Fe2+ ions to Fe3+ ions. In general, it is concluded that phosphate glasses initiate the octahedral state of the transition metals. This thesis comprises spectroscopic studies of two series of glasses, namely calcium borate and calcium phosphate doped with definite additives 0.05 mole% chromium oxide, vanadium oxide and iron oxide. The work includes UV-visible and infrared spectroscopic measurements of the prepared glasses before and after successive gamma irradiation. The glasses were prepared from chemically pure raw materials. The calcium borate glasses were melted in platinum crucibles at 1100 – 1150 °C for two hours while the calcium phosphate glasses were melted in alumina crucibles at 950 – 1000 °C. After complet melting and homogenizing, the melts were cast and annealed at the appropriate temperature. The glass samples for UV-visible spectrophotometric are the dimensions (20 x 10 x 2) (mm)3 and were perfectly grounded and polished and the measurements were carried out by a recording spectrophotometer in the range 200 – 1000 nm. Infrared spectra of the glasses were investigated for fine powder by the KBr technique using a recording FT/IR spectrometer in the range 350 – 2000 cm-1. Experimental infrared spectra of the different glasses reveal the following data: 1- The base calcium borate glass reveals infrared absorption bands which are characteristic of bond vibration of different boron-oxygen network of triangular and tetrahedral boron oxygen groups including pentaborate, triborate, diborate, metaborate, orthoborate and pyroborate. 2- The infrared spectra of all the Ca-borate glasses are quite similar but the intensity of the bands changes with composition of the glass. 3- The infrared absorption spectrum of calcium phosphate glass reveals absorption bands which are characteristic to several P-O linkages such as symmetric and antisymmetric O-P-O and P-O-P vibrations and that due to P=O end group beside the hydroxyl groups in the form of either free OH-, H2O or P-O-H. 4- The change in the composition of the glass causes obvious variation in the intensity of the absorption bands. UV-visible absorption spectra Optical absorption spectra of the undoped unirradiated calcium borate glasses reveal a cut-off band which shifts to longer wavelength by increasing the CaO content in the calcium borate glass. On subjecting this glass to successive gamma irradiation induced UV and visible band are resolved. The calculated induced spectrum reveals five induced-bands extending in the ultraviolet and visible regions. Spectral measurement of Cr-doped calcium borate glass reveals a cut-off in the UV and two visible bands and this spectrum indicates the presence of chromium in two valence states, namely Cr6+ and Cr3+. On subjecting the Cr-doped Ca-borate glasses to successive gamma irradiation, the color changes from green to deep brown and the absorption bands are shifted to lower wavelengths. The induced spectra reveal 7 induced bands in the UV-VIS regions. Spectral measurement of V-doped calcium borate glass indicates the observation of a UV cut-off at 380 nm and a visible band at about 590 – 610 nm. On subjecting this glass to gamma irradiation, the UV cut-off shifts to longer wavelength and the visible band reveals higher intensity. The induced spectrum reveals seven induced bands in all the UV-VIS regions. Spectral measurment of Fe-doped calcium borate glass reveals a cut-off in the range 350 – 400 nm. On subjecting the glass to gamma irradiation, a visible band is observed beside the UV cut-off. The induced spectrum reveals 6 induced bands extended in the UV-visible regions. Optical absorption spectra of the undoped calcium phosphate glasses reveal no visible bands but shows an UV cut-off at 328 nm. On subjecting the glasses to gamma irradiation a visible band is resolved. The induced spectrum for the calcium phosphate glass reveals 6 bands extending in the UV-visible region. The Cr-doped calcium phosphate glass spectrum reveals an UV-cut-off and two visible bands at 430 nm and a triply splitted band with peaks at 630, 650, 680 nm. On subjecting this glass to gamma irradiation, aslight change is observed. The induced spectrum of Cr-doped glass reveals six bands. The V-doped calcium phosphate glass spectrum reveals an UV cut-off and two visible bands. On subjecting this glass to gamma irradiation, a shift of the UV cut-off and is overlapped by the first visible band. The induced spectrum reveals 8 induced bands. The Fe-doped calcium phosphate glass spectrum reveals an UV cut-off and a broad near-infrared band at about 965 nm. On gamma irradiation, a new visible band is observed at 547 nm. The induced spectra reveals eight induced bands. The experimental results are interpreted on the following basis 1) For the infrared absorption spectra, it must be recalled that: a) The midinfrared region 2000 – 400 cm-1 is characterized by the appearance of the characteristic bands due to the vibrations of borate network in different arrangements. b) The near-infrared region is characterized by the absorption due to water, hydroxyl or BOH groups. c) The borate groups consist of tetrahedral BO4 groups which are generally showing their vibrational modes in the 800 –1200 cm-1 region while the borate groups consisting of triangular BO3 groups reveal their vibrational modes in the 1200 – 1600 cm-1 region. d) The infrared absorption spectra of the phosphate glasses are spread over the whole measured regions (400 – 1400 cm-1). e) The IR absorption spectra in the region 850 – 1200 cm-1 in the phosphate glasses are found to be sensitive for the different metaphosphate groups in different forms. f) The P=O double bond is found to be more strongly localized in the central position of the phosphate groups. 2) For the UV-visible optical absorption spectra, the following criteria are introduced: a) The shift of the absorption band in Ca borate glass to longer wavelength is attributed to the conversion of BO3 to BO4 without the creation of nonbridging oxygen ion. b) The intrinsic induced bands upon irradiation of the base undoped borate glass are analyzed and some of them lie in the vicinity of the alkaline earth cations and the others are not. c) The Cr-doped calcium borate glass reveals an UV band which is related to Cr6+ ions and two visible bands which are associated whith Cr3+ ions. Irradiation of Cr-doped calcium borate glass produce induced defects due to combined effects of intrinsic base borate glass and a possible photochemical reaction of Cr6+ electron capturing Cr3+ d) The V-doped calcium borate glass reveals an ultraviolet band and a visible band and they are correlated with V3+ ions. Irradiation of this glass increases the intensity of the bands which are related to progressive growth of the induced defects. e) The Fe-doped calcium borate glass reveals the same characteristic ultraviolet bands which are related mostly to Fe3+ ions and usually observed in most commerical glass due to iron impurities. Irradiation of this glass increases the intensity of the UV bands which are related to the possible photochemical conversion of some Fe2+ to Fe3+. 3) In the base undoped calcium phosphate glass, the introduction of divalent oxides (M-O bonds) are assumed to shift the UV cut-off to longer wavelengths similar to the silicate glasses. On irradiation, numerous induced defects are generated which can be attributed to electron or hole traps. a) Cr-doped calcium phosphate glass reveals an ultraviolet band which is related to Cr6+ions and two visible bands originating from Cr3+ ions. Gamma irradiation of this glass produces an ultravaiolet and another visible band with two-split peaks and the changes are related to both the intrinsic induced defects of the host glass and the possible photochemical reaction of chromium ions. b) The V-doped calcium phosphate glass seems to contain the three possible valencies of vanadium (V3+, V4+, and V5+) with ratios depending on the nature and composition the glass and condition of melting but the color of the glass indicates the presence of high ratio of V3+ ions. Gamma irradiation of this glass is observed to reveal spectral variations which are attributed to the comined effect of induced defects from the host glass and some possible photochemical process of the three valence states of vanadium ions. c) The Fe-doped calcium phosphate glass reveals charge transfer UV bands which are mostly related to trivalent Fe3+ ions. Gamma irradiation causes the increase of the intensity of absorption bands and the induced bands are correlated with both the sharing of the induced bands from the host phosphate glass and photochemical conversion of some of the Fe2+ ions to Fe3+ ions. In general, it is concluded that phosphate glasses initiate the octahedral state of the transition metals.